Book excerpt: The origins of learner corpus research go back to the late 1980s when large electronic collections of written or spoken data started to be collected from foreign/second language learners, with a view to advancing our understanding of the mechanisms of second language acquisition and developing tailor-made pedagogical tools. Engaging with the interdisciplinary nature of this fast-growing field, The Cambridge Handbook of Learner Corpus Research explores the diverse and extensive applications of learner corpora, with 27 chapters written by internationally renowned experts. This comprehensive work is a vital resource for students, teachers and researchers, offering fresh perspectives and a unique overview of the field. With representative studies in each chapter which provide an essential guide on how to conduct learner corpus research in a wide range of areas, this work is a cutting-edge account of learner corpus collection, annotation, methodology, theory, analysis and applications.